<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
  <meta charset="UTF-8">
  <title>JavaScript 数组方法 </title>
</head>
<body>
<h2>位移元素-unshift()</h2>
<p>将新元素添加到数组的开头</p>

<button onclick="myFunction()">试一试</button>

<p id="demo"></p>

<script>
  var fruits = ["Banana", "Orange", "Apple", "Mango"];
  document.getElementById("demo").innerHTML = fruits;

  function myFunction() {
    fruits.unshift("Lemon");
    document.getElementById("demo").innerHTML = fruits;
  }
</script>

</body>
</html>


<!--
Lemon,Banana,Orange,Apple,Mango

unshift() 方法返回新数组的长度。
...innerHTML=unshift() 方法返回新数组的长度。
-->